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**DRH** · 04-25-2003, 07:33 AM

Re: DIY Mic Preamp

Flo,

that pretty cool!

what other projects are you or have you worked on?

DRH

**jackson1** · 04-25-2003, 08:31 AM

Re: DIY Mic Preamp

Flo, cool project! And cool sample! Don't tell me that the sample was made only by the mic pre amp connected to the soundcard? If it was, then it's a full blown pre amp with distortion and all...

What's all the switches for on the front panel?

And the blue power supply - is that a normal component that can be bought in any radio shack?

**Infernal Death** · 04-25-2003, 09:18 AM

Re: DIY Mic Preamp

Thanks for the comments [img]images/icons/smile.gif[/img]

@ DRH
Right now i am working on a Urei 1176 comp/limiter clone. It's completely build but i had a mistake, two transistors were wrongly mounted. So i need to order some new ones (it's better that way because a wrongly mounted transistor can get damaged)
The case for the 1176 is drilled and all switches and the vu meter are mounted. So i only need those two transistors and doing more testing.
I spend about 180 Euros for the clone. Not bad considering the original lists at $2300.
In the future i plan on doing a Neve 1272 preamp and maybe a tube mic preamp and/or a EQ, preferable also tube. At the moment i really don't know about this tube stuff, we will see.

@ Jackson1
Thanks for the comment on the sample. Right now i am a little bit angry because my soundcard really ****es up the file. Oh well i guess i need to go over the whole configuration.

Hmm i hope i have understood it the right way. You think the distortion comes from the preamp ? Sorry but this is a mic preamp, has nothing to do with a guitar preamp. A mic preamp shouldn't distort a signal at all. It's purpose is to raise the low level signal from a mic to a level which is usable for the inputs of a soundcard or recorder.
My signal chain was:
Jackson Soloist -> Digitech RP3 -> BBE 422A -> Mesa Dual Rectifier -> Marshall 4x12 -> Shure SM57 mic -> Green Mic Preamp -> STAudio DSP2000 soundcard -> Cakewalk Sonar.

Now the explanation for everything on the frontpanel (from left to right):
Power switch for the whole unit
XLR input for the Taos Mic Preamp
Gain poti for the Taos
48V phantom power switch for the Taos
Impedance selector switch for the Taos
20db pad switch for the Taos
Phase reverse switch for the Taos
XLR input for the Green
Gain 12 step rotary switch for the green
48V phantom power switch for the green

As for the power supply.
This whole board, where the blue thing is on, is the power supply. The blue thing is only a transformer for stepping down the 220V main voltage (we have 220v here in europe, not 110v like you americans have) to 2x18V. And those 2x18V then will be transformed to +15V,-15V and 48V through the other parts on this part, mostly diodes and voltage regulators.
I think you can buy everything for the power supply at radio shacks since those are really common parts.

For infos, schematics and pcb layout of the green mic preamp:

http://1176neve.tripod.com/1176/id10.html

And the power supply:

http://1176neve.tripod.com/1176/id11.html

And the Taos can be found here:

http://laplaza.taos.nm.us/~fvuotto/ssmicpre.html

Hope this helps. If there are more questions i am happy to help [img]images/icons/smile.gif[/img]

Flo

**Budman68** · 04-25-2003, 09:39 AM

Re: DIY Mic Preamp

Whoa! That's a great sample to show your project results. Nice timing! Project looks great and I have to say those pics aren't bad at all for a phone cam.
[img]graemlins/toast.gif[/img]

Dave=>

**jackson1** · 04-25-2003, 10:51 AM

Re: DIY Mic Preamp

Originally posted by Infernal Death:
You think the distortion comes from the preamp ?

<font size="2" face="Verdana, Helvetica, sans-serif">No no. I know what a normal mic pre-amp is, but i got confused when you gave us that metal distorted sample saying it was a file done with the green mic pre-amp. My fault.

Thanks for the extensive explanation, sounds really interesting. Is the compressor / limiter a 100% copy of the Urei? I don't know the Urei, but i will ask google in just a few seconds what it is [img]images/icons/smile.gif[/img]

**jackson1** · 04-25-2003, 10:55 AM

Re: DIY Mic Preamp

Googles answer on Urei 1176 below. That's an oldie! And Jackson uses it! (Michael that is):

Mono solid state compressor/limiter, using FET gain reduction. Stereo linkable with 1176SA. Designed by Bill Putnam in the late 1960s, the 1176 evolved from the Universal Audio 175 and 176 vacuum tube limiters. Universal Audio claim it was the first true peak limiter with all transistor circuitry, and as the modified 1176LN (low noise) version it went on to become an absolute classic. Few serious studios have been without one since the early 1970s.

**Infernal Death** · 04-25-2003, 11:13 AM

Re: DIY Mic Preamp

Yes the 1176 is very old. But like the google text states it's a true recording classic.
From what i know the version i do is a nearly 100% copy. The layout was made from a 100% original schematic. The original pcb layout of the urei is much bigger, the one i am doing has a euro card format (10x16cm, that's 3,94x6,3 inch) so it's smaller.
A difference is in the output transformer. Don't know what the original ureis are using but mine uses a Lundahl transformer (Lundahl is from sweden). But those transformers have the same quality as the original ones.
The designer of this 1176 clone said that his clone sounds really like the original ones. There are some different versions of the urei and the designer said that his clone sounds like the g-version but i am not quite sure.

Here is a pic from someone else who did this clone (two to be exact):

Flo

**DRH** · 04-25-2003, 03:42 PM

Re: DIY Mic Preamp

Flo,

are you doing the pc board layout yourself? If so, what layout software do you use?

DRH

**jackson1** · 04-25-2003, 04:04 PM

Re: DIY Mic Preamp

Have you heard/used the 1176 clone in your guitar setup? How does it perform?

As far as valve projects - why not get the schematics for the Engl E530 pre-amp and do a copy? I'll take one [img]images/icons/grin.gif[/img]

**Infernal Death** · 04-25-2003, 05:20 PM

Re: DIY Mic Preamp

@ DRH
For now i don't do the pcb layout myself. From what i understand there is quite some skill needed for doing a good pcb layout, for example doing the grounding scheme right.
I have a shareware version of circuit maker 2000 but i had no time working into it.
Since i am a beginner in DIY things i want to use premade pcb layouts. Maybe sometime in the future i will start to make own pcb layouts from schematics.

@ Jackson1
No i haven't used the clone since this is my first clone of the 1176 i have done and it isn't ready yet. But i think it will really be useful since it's such a classic piece of recording equipment.
For the time now i want to stay with recording gear but well maybe i try some tube guitar gear in the future. But for now i want to practice DIY a little more with solid state things because tubes with their high voltage are quite dangerous [img]images/icons/smile.gif[/img]

I hope i can finish my 1176 in the near future. After that i guess i will start building a Neve 1290 but haven't decided yet.

Flo

**OklaStrat** · 04-26-2003, 09:51 PM

Re: DIY Mic Preamp

Flo -

NICE job! One of these days I'm going to build a tube mic preamp, but one of the more painful things when you do that is shelling out fairly big $$$ for the transformers. [img]images/icons/frown.gif[/img]

I'd love to see some schematics - email me at [email protected] if you would. Maybe we could trade some tips or schematics or something...

Pete

**Infernal Death** · 04-27-2003, 04:00 AM

Re: DIY Mic Preamp

Pete sure i drop you a mail in the next days. Is there anything special you want ? Mic Preamps ? Channel Strips ? Compressors ? EQ's ?
I have some schematics from SSL, Neve, Amek, Focusrite, API, Manley, John Hardy and some others.
It's mostly the higher end stuff (for example the Red 6 from Focusrite).

In the meantime check this site out:

http://gyraf.dk/gyraf2/gy_pd/gy_pd.htm

It's a really amazing DIY site. That's where i have all infos, schematics and pcb layouts for the 1176 (this clone is called the G1176). This guy from the site, Jakob Erland is building professionally recording equipemnt so he definitely knows what he does.
And he often respondes on the recording org tech talk forum, a very cool message board for DIY recording stuff.
Maybe you wanna check it out, lots of experienced and great members:
http://www.recording.org/cgi-local/ubb/ultimatebb.cgi
There is also a newsletter for the tech talk section.

Pete, if you wanna do a tube mic preamp you should check out the G9 from Gyraf Audio:
http://gyraf.dk/gyraf2/gy_pd/g9/g9pd.htm
There is all the info you need to start right away.

Yeah i know transformers are really the expensive parts with DIY. Problem is that all higher end stuff uses transformers. The g1176 uses a output transformer (and a optional input transformer which i haven't bought because i heard the difference is only small) and this output transformer was with over $50 the most expensive part on the whole project, right before the VU meter with around $40.

Drop me a line at [email protected] or write here if you want to have some special schematics. I got most of my schematics either from searching from the net or from the tech talk of recording.org.

Flo

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